telecom@ucbvax.UUCP (01/29/86)
Just today I found the real answer to a question which has piqued my
curiosity for many years: What does the `E' and `M' stand for in the term
``E&M signaling''? No one - including people I have asked who work for the
"Bell System" - has ever been able to answer other than "the letters have no
meaning, but were arbitrary lead designations in a long-forgotten signaling
system".
According to an AT&T Long Lines training manual from the early 1940's
(which I recently rescued from the trash), the `E' stands for ``Ear'', and the
`M' stands for ``Mouth''. Think about it; it actually makes SENSE.
Telecommunications history has always been an interest of mine, and
one of my favorite reference sources is a two volume set entitled: "A History
of Science and Engineering in the Bell System", which is profusely illustrated
and covers the time period of 1875 to 1925 in Volume I, and 1925 to 1975 in
Volume II. These books were both written and published by Bell Telephone
Laboratories. I bought my set directly from the BTL publications department
about ten years ago. I don't know if copies are still available, but I would
highly recommend these books for anyone with similar interests. There are also
good sections on the history of computers and military electronics.
As detailed (~ 1,900 pages total) as these books are, though, they still
couldn't answer the E&M lead question...
==> Larry Lippman @ Recognition Research Corp., Clarence, New York <==
==> UUCP {decvax|dual|rocksanne|rocksvax|watmath}!sunybcs!kitty!larry <==
==> VOICE 716/741-9185 {rice|shell}!baylor!/ <==
==> FAX 716/741-9635 {G1, G2, G3 modes} duke!ethos!/ <==
==> seismo!/ <==
==> "Have you hugged your cat today?" ihnp4!/ <==telecom@ucbvax.UUCP (01/30/86)
In article <8601300934.AA08968@ucbvax.berkeley.edu> kitty!larry@SEISMO.CSS.GOV writes: > > Just today I found the real answer to a question which has piqued my >curiosity for many years: What does the `E' and `M' stand for in the term >``E&M signaling''? No one - including people I have asked who work for the >"Bell System" - has ever been able to answer other than "the letters have no >meaning, but were arbitrary lead designations in a long-forgotten signaling >system". > According to an AT&T Long Lines training manual from the early 1940's >(which I recently rescued from the trash), the `E' stands for ``Ear'', and the >`M' stands for ``Mouth''. Think about it; it actually makes SENSE. another good one is the original meaning of the tip and ring lines. funny thing about >ring<, is that it has nothing to do with the ringer in the phone. the story i got from a telecommunications guru was there once was a little plug, looked a lot like a coax plug, and the middle (the tip) was called tip, and the outside (the ring) was called ring. kind of makes you wonder about terms like UNIX mean :-> curt
ron@BRL.ARPA (Ron Natalie) (01/31/86)
re >another good one is the original meaning of the tip and ring lines. >funny thing about >ring<, is that it has nothing to do with the ringer in the >phone. the story i got from a telecommunications guru was there once was >a little plug, looked a lot like a coax plug, and the middle (the tip) was >called tip, and the outside (the ring) was called ring. Give me a break. Of course tip and ring have nothing to do with the ringer. The standard "PHONE" plug has two conducters one on the tip and the other on the sleeve or "ring." The "ring" side is more descriptive of the jack where the contact actually is a ring. UNIX by the way is a PUN, but the letters are not an acronym for anything. -Ron
telecom@ucbvax.UUCP (01/31/86)
In article <8601300934.AA08968@ucbvax.berkeley.edu> you write: > > Just today I found the real answer to a question which has piqued my >curiosity for many years: What does the `E' and `M' stand for in the term >``E&M signaling''? No one - including people I have asked who work for the >"Bell System" - has ever been able to answer other than "the letters have no >meaning, but were arbitrary lead designations in a long-forgotten signaling >system". > According to an AT&T Long Lines training manual from the early 1940's >(which I recently rescued from the trash), the `E' stands for ``Ear'', and the >`M' stands for ``Mouth''. Think about it; it actually makes SENSE. > Telecommunications history has always been an interest of mine, and >one of my favorite reference sources is a two volume set entitled: "A History >of Science and Engineering in the Bell System", which is profusely illustrated >and covers the time period of 1875 to 1925 in Volume I, and 1925 to 1975 in >Volume II. These books were both written and published by Bell Telephone >Laboratories. I bought my set directly from the BTL publications department >about ten years ago. I don't know if copies are still available, but I would >highly recommend these books for anyone with similar interests. There are also >good sections on the history of computers and military electronics. >As detailed (~ 1,900 pages total) as these books are, though, they still >couldn't answer the E&M lead question... > >==> Larry Lippman @ Recognition Research Corp., Clarence, New York <== >==> UUCP {decvax|dual|rocksanne|rocksvax|watmath}!sunybcs!kitty!larry <== >==> VOICE 716/741-9185 {rice|shell}!baylor!/ <== >==> FAX 716/741-9635 {G1, G2, G3 modes} duke!ethos!/ <== >==> seismo!/ <== >==> "Have you hugged your cat today?" ihnp4!/ <== [] A variety of interesting publications are still available from AT&T. A listing of the texts in the now 5 volume series that Larry mentions two of are listed below: DESCRIPTION SELECT CODE PRICE A History of Engineering and Science in the Bell System 500-467 $47.00ea The Early Years (1875-1926) This first volume the AT&T History Series of Engineering and Science in the Bell System offers a detailed over- view of the first 50 years of telephone technology. The narrative goes well beyond a simple statement of events to deal with the "how" and "why" of technological innovation. A History of Engineering and Science in the Bell System 500-468 $47.00ea National Service in War and Peace (1925-1975) This second volume focuses on the Bell System's contri- butions to national defense before and during WWII and in the cold war missles crises that followed. The central subject is engineering for urgent national defense - how the technology of communications was adapted quickly and in many ways to the compelling needs of a nation at war. (Also, detailed descriptions of radar development, Nike, Nike Ajax, Nike Hercules, Nike II, Nike-X, Sprint, Spartan, Sentinal, Safeguard missle and ABM programs, sonar, early gun directors, you-name-it. (wts)) A History of Engineering and Science in the Bell System 500-469 $47.00ea Switching Technology (1925-1975) This third volume chronicles how switching, which during the early years was characterized by the introduction of and improvements in manual switchboards, became completely automated. Discussed are major innovations that produced generations of switches operating at higher and higher speeds and handling functions of increasing complexity and flexibility. A History of Engineering and Science in the Bell System 500-470 $47.00ea Physical Science (1925-1980) This fourth volume records AT&T Bell Laboratories research work in the area of physics, chemistry, and material sciences. It tells the stories behind major discoveries and inventions, including accounts by some of the people involved in the work. Of special interest is an account of the genesis of the transistor, including reminiscences written expressly for this volume by W.H. Brittain. A History of Engineering and Science in the Bell System 500-471 $47.00ea Communications Sciences (1925-1980) (No catalog description printed for this volume - wts) The above may be obtained from: AT&T Customer Information Center Marketing Department P.O. Box 19901 Indianapolis, IN 46219 Make checks payable to: AT&T Technologies Inc. Phone orders: 800/432-6600 Operator 102 Outside Continental U.S. 317/352-8557 AMEX MasterCard VISA Foreign Orders - Payment Must be made by International Money Order or Checks Drawn on U.S. banks payable in U.S. Dollars. To receive a complete catalog of various other AT&T publications, call the 800 number shown above, and ask Operator 102 for Select Code 000-011 - Commercial Sales Documentation Catalog. William T. Sykes AT&T Federal Systems Burlington, NC 27215 burl!wts
telecom@ucbvax.UUCP (01/31/86)
The BTL classes use the Ear and Mouth designations to help you remember which is which. Frankly I like the Ear & Mouth story better, but I ran across this: "Basic Telephone Switching Systems", second edition, David Tally, Hayden Publishing, p.41 `The E and M system received its name from historical designations on old circuit drawings. The E referred to the middle "e" in received and the M from the "m" in transmit.' tim born ...ihnp4!ihlpg!timborn